M14. There's more surface area there. How are you planning to make the squares?
I just printed out a thing of digital camo of different sizes then used it as a stencil. Sorry forgot to take pictures while doing half but might still make a instrucable
i gonna say m4, but DONT do the whole thing. this make it look cheap, or unprofessional. if you are going with the m4, ill suggest doing the handguards, the grip and the stock, but not the buffer-tube (the tube that holds the actual stock).If you chose to do the m14 though (unless its wood finish, that would look terrible), im gonna say the same thing. probably do the stock all the way up to the curve of the grip, and the entire upper receiver. in the end though, its really going to be YOUR choice.
well, it depends on how you want to paint it, where you want to play, etc. if you paint the m14, but want to play in an urban environment, it will give you away pretty fast. I sugest painting the gun you use less.